const singer = [{
		name: '周杰伦',
		age: 34
	},
	{
		name: '许嵩',
		age: 34
	},
	{
		name: '邓紫棋',
		age: 44
	},
	{
		name: '张碧晨',
		age: 44
	},
	{
		name: '薛之谦',
		age: 44
	},
	{
		name: '封茗囧菌',
		age: 44
	},
]
Array.prototype.my_filter = function(callback) {
	const res = []
	for (let i = 0; i < this.length; i++) {
		callback(this[i], i, this) && res.push(this[i])
	}
	return res
}

const newSinger = singer.my_filter((item, index, arr) => {
	return item.age > 40
})
console.log(newSinger);
